Flags (or compiler options) are nothing but ordinary command line arguments passed to the compiler executable. Assuming you are invoking g++ from the command line (terminal): $ g++ -std=c++11 your_file.cpp -o your_program or $ g++ -std=c++0x your_file.cpp -o your_program if the above doesn’t work.
Here is a solution simpler than Johannes Schaub – litb‘s one. It requires C++11. #include <type_traits> template <typename T, typename = int> struct HasX : std::false_type { }; template <typename T> struct HasX <T, decltype((void) T::x, 0)> : std::true_type { }; Update: A quick example and the explanation on how this works. For these types: … Read more
C99 way, also supported by VC++ compiler. #define FOO(fmt, …) printf(fmt, ##__VA_ARGS__)
Yes, use -E -dM options instead of -c. Example (outputs them to stdout): echo | gcc -dM -E – echo | clang -dM -E – For C++ echo | g++ -dM -E -x c++ – echo | clang++ -dM -E -x c++ – From the gcc manual: Instead of the normal output, generate a list … Read more
This is a known bug under MinGW. Relevant Bugzilla. In the comments section you can get a patch to make it work with MinGW. This issue has been fixed in MinGW-w64 distros higher than GCC 4.8.0 provided by the MinGW-w64 project. Despite the name, the project provides toolchains for 32-bit along with 64-bit. The Nuwen … Read more
To figure out what the linker is looking for, run it in verbose mode. For example, I encountered this issue while trying to compile MySQL with ZLIB support. I was receiving an error like this during compilation: /usr/bin/ld: cannot find -lzlib I did some Googl’ing and kept coming across different issues of the same kind … Read more
SFINAE only works if substitution in argument deduction of a template argument makes the construct ill-formed. There is no such substitution. I thought of that too and tried to use std::is_same< T, int >::value and ! std::is_same< T, int >::value which gives the same result. That’s because when the class template is instantiated (which happens … Read more
gcc and g++ are compiler-drivers of the GNU Compiler Collection (which was once upon a time just the GNU C Compiler). Even though they automatically determine which backends (cc1 cc1plus …) to call depending on the file-type, unless overridden with -x language, they have some differences. The probably most important difference in their defaults is … Read more
To be able to use std::unordered_map (or one of the other unordered associative containers) with a user-defined key-type, you need to define two things: A hash function; this must be a class that overrides operator() and calculates the hash value given an object of the key-type. One particularly straight-forward way of doing this is to … Read more
The GCC FAQ has an entry on it: The solution is to ensure that all virtual methods that are not pure are defined. Note that a destructor must be defined even if it is declared pure-virtual [class.dtor]/7. Therefore, you need to provide a definition for the virtual destructor: virtual ~CDasherModule() { }